Old post, but thought I'd share my two cents since the dude didn't get an answer.....

I've done this alot with my band. you're correct in it being C Major, but G Mixolydian is easier to work with IMHO simply because it sounds better resolving on that G. For the "Yeah, yeah, yeah" parts try just hitting the vocal notes. Then, a really cool switch to D Mixo or Blues over the D chord, then G Blues over the G. Moves pretty fast but a lot of fun to play.

A standard major scale is also known as the "Ionian". The "Mixolydian" scale uses the same notes as the major/Ionian scale but starts at the note a fifth above. So, if I haven't memorized the pattern of whole/half steps for a Mixolydian, all I need to do is look to see what note is a fifth lower and then use the notes from that Major/Ionian scale. So for a "G Mixolydian," I ask myself "what note is a fifth lower than G?" and my answer is C. So a G Mixolydian would use the same notes as a C Major/Ionian, but instead of starting at C, we start at G, like this:

G, A, B, C, D, E, F (ad infinitum)

Same available notes, different order.

Because I see this from the perspective of a keyboard, I'm not seeing individual scales, but instead a continuum of "available" notes from the lowest of frequencies to the highest. To me, using the terms Ionian, Dorian, Phrygian would really only come into play if someone took a snapshot of the keyboard and asked me to describe what I saw. If the key furthest to the left were the root note, a C in our example above, if asked, I could accurately describe it as a C Major or Ionian scale. Similarly, a D Dorian if the first note were a D. Since I'm a visual learner, and others might be too, I'll try to depict this visually:

So how do you know when someone is playing in G Mixolydian as opposed to C Ionian? They're all the same notes, so is it a matter of examining the fingerings used by the musician? Or is there something that I'm missing in my Ionian-centric thinking?

What's more, we still haven't addressed the "why" behind G Mixolydian being the recommended scale.

You mention that it's better for "resolving on that G."

I have an equally limited understanding of resolution. I know that resolving from the fifth to the first is pleasing to the ear. If we're talking individual notes, that's the jump from G to C. If we're talking triads found within a major scale, that would be G major -> C Major. If we use the I, ii, ii, IV, V, vi, vii Roman Numerals, we're talking V->I. Sounds great. Sounds complete. Could easily be the ending of a song (which I believe is why it is called a "Perfect Cadence.") Sounds better than the resolution of a fourth to a first (F -> C, F major -> C Major, IV->I, known as an "Plagal Cadence.")

So what is meant by "resolving on that G?" From the major triads found in the song, I'd say that the song was in the key of C. With C as a root note, G major would be the V chord. So wouldn't the resolution actually be G -> C? Or are you saying that you like to end your riffs/phrases on the G note? Or perhaps that you like ending them when the background chord is a G major?

Could someone please help me out here? I feel like I can grasp the theory, but that putting it into practice is beyond me. (My "solos" consist of arpeggiating the underlying chords far, far too often).

You definitely have a good technical understanding of theory, but I think you're just making it a whole lot more complicated than it ought to be.

How I got G Mixolydian was by just copying as much as i could from Jerry's Good Lovin' solo's that I own. It seems he's ending alot of phrases on the G. You seem to have a knowledge of the modes, so they could all technically work i guess. I think if it's easier for you to look at it as C Ionian, I'd say by all means do that. What's easiest for me though, because I think resolving alot of the phrasings in G sounds cool, is G Mixo.

Just so I'm clear, you're saying that the solos tend to end on a G note? Or that his phrases tend to end during the bars when the background chord is a G major?

If its the former, I think I understand what you're saying. If the phrases end on a G note, that seems to be your grounding force. Everything comes back to it. So I can certainly see why you'd call it a G mixolydian scale.

That was the part I never got. I always felt like the strongest pull would be to the root note. And perhaps that was limiting my thinking. Maybe I should just tell myself "tonight, i'm going to resolve to a G (or randomly choose another note)" and try to find a phrase that will end there.

I hate the idea of intellectualizing music, for fear that it'll suck the soul right out of it, but perhaps that what I need to do to break through this wall I keep running into with my soloing.

definitely the former...nothing really to do with where the G chord is for the first part of it. It changes, however during the "yeah yeahs" and the D and G (all you need...all you really need) chord though, play the changes there. Just try it.

I would approach the deciphering of this solo as being anologous to the Touch of Grey solo... basicaly an arpegio fest based on the available chord forms chosen on the fly, loosely tied together with basic chromatics.When Salmon swim upstream and up waterfalls and stuff like that, it's an incredible feat of nature, but bottom line, they take the path of least resistance.Same with Jerry's solo's!